The snow came, but was indeed light and is mostly gone already. It’s not even supposed to freeze overnight. It’s still cold, just not the major death-to-all-fools-who-venture-outdoors that the news media might prefer. Maybe next time.

I rushed home and, after delays from trying to find and gather stuff (never organize; it’s just not worth it!), I reflashed the ECU with the latest firmware (v2.890), wired to support stepper IAC (Idle Air Control) and connected up to the JimStim.

One of the first things I had to do was some wire mods on the ECU board. By default, the stepper feature is not physically connected on MegaSquirt. The output connections are left unconnected because they can be used for any of several options; stepper IAC is just one of the options. The mod itself is very simple, adding five jumper wires on the bottom of the board.

After lots of experimenting, I also had to perform another minor mod, bypassing some current limiting resistors that are built in to protect the circuit board and wiring from shorts. I guess I will have to just leave my shorts at home.

After that, it was just setting parameters, which was a very much experimental “try this and observe” process. I eventually arrived at some workable values.

One thing to keep in mind is that my throttle body in it’s original Ninja 650 form uses a stepper motor to operate sub-throttles, but there is also a cam on the end of that shaft that operates the main throttle butterfly to provide fast idle. As I discovered experimentally, the subthrottle is completely open when the cam is operating the main throttle as far as it can. The subthrottle is at about 60% open when the cam disengages the main throttle completely. Although the partially closed subthrottle is not expected to affect normal engine operation until the main throttle is more than 60% open (and maybe not even then), I will probably remove the butterflies anyway.

One thing that I found confusing is that I was erroneously thinking in kind of “absolute position” terms. At power up, the ECU moves the IAC 350 steps (Start Value) to ensure it is open all the way. I thought of that as position 350, thinking that the system would then want to close the IAC down to 0 as the engine warms up.

I was wrong.

The two main states of the IAC, power-up and operation, are relative to one another. At power up, the ECU will use the Start Value to open IAC all the way with, in this case, 350 steps in one direction. Once the power-up routine is finished, that position becomes 0 and all temperature points are expressed as steps in the other direction from there. In my case, it then takes 145 steps in the other direction to completely close the IAC, or more precisely, to completely disengage the fast idle cam from the main throttle. It is 0 and 145 that are needed to generate the IAC Steps curve.

The other major value arrived at experimentally is the Time Step Size, basically the time between stepper pulses. The smaller the time, the quicker the motor moves, at least up to a point. I found that it seems reliable at 0.5 mS, which is way down from the default of 2.5 mS. I decided to give it a little margin and set it at 0.7 mS. It moves quickly, smoothly and quietly there.

For the entertainment value, at 5.0 mS, it sounds like an old 5-1/4″ floppy disk drive and at 10 mS, it sounds like a blender stuck on a piece of ice.

Sorry for the poor focus, but here is a bit of Blackberry video of it working.

Finally, it seems that operating the motor in the ‘Always On’ mode, where voltage is left on the motor to keep it stationary, makes the motor and driver chip run pretty hot. That mode is not really needed here, so I am running it in ‘Moving Only’ mode, which only sends power to the motor to effect an actual position change.

So, to summarize, it took me about 5 hours to make MegaSquirt open and close a little motor, but I think it still counts as a big step!

I’m sure I wasn’t the only one with a crazy month. It’s been go go go go go. I think the last of it is done.

Well, except for the weather… Expecting a bit of snow tomorrow, though it’s not expected to be much nor to stick around.

Santa thought organizing my tools might help me be good for next year, so he brought me a big rolling tool chest/organizer. I loves me some Santa. Lucky for me, Santa’s pretty cute, too.

Now that I’m not spending every evening getting the house ready for guests or shopping or whatever, I should FINALLY be able to start playing.

Today was very nice and, difficult though it was to do so, we worked on stuff around the house instead of going for a ride.

Filled the back of my truck with trash and other discardables from the carport. I still had the boxes that various Harbor Freight items came in, such as the air compressor, engine stand, welding cart, tool box cart and soda blaster. Most were at least wrinkled from humidity, if not completely warped from rain. Fall leaves, countless shopping bags (mostly from AutoZone, which is probably a hint that I should be a stockholder) and no shortage of used paper towels littered the area.

We had some aluminum frame windows that were promised to our neighbor long ago. They were stored quite literally as far back in the carport as possible. Because of the work today, I was able to clear a path all the way back there and retrieve them for him. Tiny karma gain.

I worked from about 10:30A or so until 7:00PM. If you look at it critically from a before and after point of view, all I did was make room for one more trike. More importantly, though, 2/3 of the space is clean enough to easily roll things around. Another good evening’s work and I may be able to roll the purple trike all the way back where the best work space is and work on it at home for a while.

So long as it’s not devastatingly cold or actively precipitating, the space isn’t too bad. I have a 30,000 BTU heater almost exactly like this one and it keeps a decent working area warm. I may try to cover the gap between the top of the fence and the roof of the carport to keep some of that heat enclosed.

I have been essentially storing the trike at the BTW clubhouse. The *intent* was to have it down there to work on it, but mundane life has ensured that I have had little time to pack up and head down there, compounded by the need to keep my footprint there at a minimum for the holidays. Now that our (probably) final holiday shindig there has concluded, perhaps I can make some progress working on it down there.

But first, I want to get some stuff done that is arguably easier to do at home, such as the welding I need to do to complete the adapter plate.

An acquaintance is building an airplane from a kit and whilst perusing the builder’s guide on their website, I stumbled upon a piece of advice that I had inadvertently ignored: “[your construction space] should be as close to home as possible. Driving any distance at all to work on the [airplane, trike, whatever] will drive the time to build up by unimaginable amounts. One [airplane kit] builder estimated that having to drive only four miles to work on his project doubled his construction time.”

It also says that “Good light, air conditioning or heat as the climate requires, good ventilation and good organization are essential. An uncomfortable place to work means hurried, often poor, work.”

In my case, those are almost exclusive of one another. The clubhouse is a fairly well lighted space that has a roof over it, a decent amount of work space and a few specialty tools that are absent at home. It is, however, 4-5 miles from home.

My driveway is covered but otherwise essentially outdoors, and crowded with stored tools and vehicles. It is, however, very close to home.

I finally got started on the throttle body adapter!

Using the gasket that came with the intake as a pattern, I cut a piece of 3/16″ plate to shape and cut the holes in it.

I struggled for a couple of hours trying to fit existing tubing and a couple different O-rings to the base of the throttle body. I tried using exhaust reducers. They came the closest to fitting and I guess it was worth trying, but the only combination that seems likely to work will be to gently stretch a 2″ fitting so that the smaller diameter end is very slightly larger than it is now. It will not be easy to do that and keep it round and O-ring-sealing smooth.

Luckily, I may not need to. After noticing that my hatless short sleeve work uniform was inadequately warm for the falling temperatures in the carport, I came inside and found that a best offer I’d submitted on a pair of actual EX650 intake boots was accepted.

There is a slim chance that I may have to remake the plate for these intakes, but it will be worth it to not have to deal with the precision required to seal and attach the throttle bodies to the intake manifold!

Since I’m waiting for parts now, I thought this might be a good time to apply some thinking out loud time to X-Tau acceleration enrichment.

In short, this is an enrichment that compensates for how much of the injected fuel sticks to the walls of the manifold. This is another one of those things that I’m so very glad that someone else had to figure out. As astonishingly brilliant as I am, I’m not sure it would have occurred to me. Anyway, the problem is that a percentage of the fuel going into the manifold sticks to the walls. This fuel eventually evaporates and makes it to the cylinder, only to be replaced by more injected fuel. In a steady state load, the sticking and evaporating fuel reach an equilibrium, but it can become a significant factor with changing loads, making the mixture unexpectedly lean during acceleration and unexpectedly rich during deceleration.

It would seem to me that intake tract length could be a large factor in this phenomenon, and in my configuration will in fact have a relatively long intake tract.

On Buzz, the intake tract was about 5 inches between the injector and the intake valve and there just isn’t much manifold wall to stick to. That doesn’t mean that it’s completely not a factor, only that its a small factor.

On the VW, in my configuration at least, there is a good couple of feet of intake tract between the injector and the intake valves. Additionally, the intake tends to be cooler near the injector and warmer near the valve. This temperature differential is why most VW manifolds have tubes to circulate hot exhaust gases through the manifold, so that the temperatures along the intake tract will be more consistent. A cold manifold will condense vaporized fuel, exacerbating the manifold wall wetting problem.

Honestly, getting the engine running will not require much attention to X-tau compensation, but tuning it for best performance will.

Sometimes, it sucks to work.

I have spent most of what would otherwise have been a great week to work on the dragon trike in New Mexico working. I enjoy New Mexico and I like our people there, but I wanted to stay home.

Even after spending the week out of town, I wasn’t going to forsake the Dallas appearance of the International Motorcycle Show to work on the trike. Overall, the show was pretty good. Enjoyed seeing the Ducati stunt team. Nothing sounds quite like a Duck. Found that for all the hype, the Honda Fury is unridable for the same reason most other choppers are. Long bike, long seat, long pegs, short bars. Who want’s to ride when folded into a cramped “C”?

The bigger problem with the show was with what was missing. This is my third year attending. The first year it was held at the Fort Worth Convention Center. Besides being my home town and essentially walking distance from work, the Ft Worth show seemed much…. I don’t know, “fuller”. More vendors, more manufacturers, more.. stuff. Last year in Dallas, there were fewer bike vendors than the previous year in Fort Worth. Absent in Dallas last year were names such as Moto Guzzi and Vespa and Kymco that were prominent in Fort Worth the year before. Similarly, some notables were missing this year, like Victory, KTM, Triumph, and of course, Buell.

We still managed to have fun and shop a lot.

One thing that occurred to me suddenly whilst I was in the Kawasaki pod was that my plan to use the throttle bodies that were apparently from a Ninja 650 might be simplified by the acquisition of some stock parts.

One of the part fabs I will need to do is some kind of adapter between the TB and the manifold. The Ninja (or the Versys; they use the same engine) has to connect the TB to the engine, so maybe their connector can be adapted to my manifold easier than building something from scratch. According to Kawasaki Parts House, they are only about $20 apiece. Unless i can get RIGHT on fabricating something, I will probably order a couple of them.